Friday, 1 May 2015

For adults, let alone children, time is a tricky concept to comprehend. In our culture, we carve it up into somewhat arbitrary chunks and attribute words to those durations: 60 seconds in a minute, and 60 of those in an hour and so on. We also have a sense of what these durations feel like. Children start using these time-related words at around the age of two or three years, even though they won't master clocks until eight or nine. This raises the question – what do young children really understand about duration words?

Katharine Tillman and David Barner began by asking dozens of three- to six-year-olds to compare several pairs of durations (e.g. Farmer Brown jumped for a minute. Captain Blue jumped for an hour. Who jumped more?). As well as minutes and hours, other durations used were seconds, days, weeks, months and years. This test showed that by age four, the children were tending to get more of these questions right than would be expected if they were just guessing. With increasing age, the children got better at the task. In other words, from age four and up, children have a sense of the rank order of different duration terms.

What young children don't have, according to the findings from further experiments, is a sense of the actual lengths of time that these terms refer to. When the comparison test was repeated, but with different amounts of each duration, the children were flummoxed. Take, for example, the question "Farmer Brown jumped for three minutes. Captain Brown jumped for two hours. Who jumped more?" As adults, we aren't thrown by the minutes outnumbering the hours by three to two, because we know that an hour feels much longer, and is by definition 60 times longer. However, even five-year-olds, who know well the principle that an hour is longer than a minute, were thrown by these kinds of comparisons. This suggests they don't yet have a very good understanding of the formal definitions of duration words, nor what the different durations feel like.

In another experiment, five- to seven-year-old children were asked to place different duration words along a horizontal line after the far-left end had been described to them as the location for "something very short, like blinking" and the far-right end as "something very long, like the time from waking up in the morning to going to bed at night". Again, before age 6 or 7, the children really struggled with this – even with the order correct, they tended to space them out inappropriately, compared with how an adult would do it. Six and seven-year-olds who knew the formal definitions for the duration words tended to perform better.

These findings mirror what's been found for the way children use words for other concepts like numbers and colours. Before they map the words onto actual perceptual experiences, they understand that words in a given domain are related, and (in the case of numbers and time), they have a sense of the relative magnitude of the concepts. But it's only after using such words for some years, and learning their formal definitions, that they fully connect the experience of the concept (such as the length of an hour, or the physical magnitude of a number) with its corresponding word.

"Our results indicate that proficiency in estimating the absolute time encoded by duration words emerges relatively late," the researchers said, "and may even rely on formal instruction in [primary] school."